Second Neuroscience lecture

Second Neuroscience lecture - Cognitive Neuroscience,...

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Unformatted text preview: Cognitive Neuroscience, Neuropsychology and other cool brain stuff… other Michael Hout April 10, 2007 Some fun brain facts: Some Did you know that we only use 10% of our brains??? brains??? Yeah, well we don’t. Yeah, You are using a huge portion of your brain even when you sleep. when “Someone has taken most of your brain Someone away and you probably didn't even know it. Well, not taken your brain away, exactly, but decided that you don't use it. It's the old myth heard time and again about how people use only 10% percent of their brains. While for the people who repeat that myth, it's probably true, the rest of us happily use all of our brains.” Benjamin Radford Some facts (1); Structure: Some The average brain weighs only 3 lbs. However, it contains more than 100 billion neurons, each linked to as many as 10,000 others. The brain is suspended in cerebrospinal fluid (CSF). Without this dense fluid, the brain essentially collapses in upon itself. Facts (2); your selfish brain: Facts Unlike other tissues, the brain can burn only pure glucose, and has little capacity to store significant reserves. to In adults, although only 2 percent of body weight, the brain consumes 20% of the available oxygen and glucose. available At birth, the brain is 10% of body weight and consumes up to 65% of the body’s 65% of energy. energy. So, how do we figure out what does what? does A large portion of what we now know about the brain has been inferred from studies of those who experience brain damage. Causes of damage: stroke, lesion, traumatic head injury, graduate school, infection, disease, etc. infection, Disruption of Blood Flow to the Brain Disruption Occlusions in the blood flow to the brain can result in stroke and subsequent tissue death and loss of function. These angiograms show occlusions in two different cerebral arteries. Seriously though… Seriously Researching brain damage is enormously important. important. A helpful analogy: assuming you don’t know anything about cars, one way to learn how the engine operates would be to take individual components out. to If you take away the oil, what happens? If Cognitive Neuroscience and Neuropsychology Neuropsychology Cognitive neuroscience iis an academic field concerned s Cognitive with the scientific study of biological mechanisms underlying cognition, with a specific focus on the neural cognition, substrates of mental processes and their behavioral manifestations. It addresses the questions of how psychological/cognitive functions are produced by the neural circuitry. Neuropsychology iis a branch of psychology and Neuropsychology s psychology and neurology that aims to understand how the structure neurology that and function of the brain relate to specific psychological brain relate processes and overt behaviors Language Areas of the brain: Language The Neurocognition of Language… Language one of the first cognitive abilities suspected of being localized to particular brain regions. particular Broca: Broca Paul Broca (1861) Broca (1861) noted that only damage to the left hemisphere produced an aphasia (loss of language ability). language He hypothesized that language functions were localized in the frontal lobe of the left hemisphere. hemisphere. Broca’s Area and Broca’s Aphasia Broca’s associated with lesions to the left inferior posterior frontal lobe (Broca’s area) posterior Broca’s area is responsible for language production production Broca’s aphasia is characterized by difficulties in speaking difficulties speech is ungrammatical; typically a series of isolated words strung together of Broca’s aphasic asked about an upcoming dental appointment: upcoming “Ah ... Monday ... ah Dad and Paul ... And Ah Dad ... hospital. Two ... ah ... doctors ... And ah ... thirty minutes ... and yes … ah ... hospital. And er Wednesday ... nine er Wednesday o'clock. And er Thursday, ten o'clock ... er Thursday, doctors. Two doctors .. and ah ... teeth” Broca’s Aphasia Broca’s – hesitant, agrammatic speech (nonfluent) hesitant, agrammatic – function words omitted; content words function preserved preserved – comprehension remains relatively intact – anomia (difficulty naming objects) Broca’s Aphasia Broca’s Broca’s aphasics understand the speech of others others their difficulty is generating coherent speech not simply a motor difficulty – they can they often sing fairly well often the writing of Broca’s aphasics is usually at least as impaired as their speech (agraphia) Karl Wernicke (1875) Wernicke (1875) argued that the brain regions subserving subserving auditory language auditory comprehension were also located in the left hemisphere. hemisphere. Now known there are two principle brain regions specialized for language processing – Broca’s area Broca’s and Wernicke’s area. Wernicke’s Well established that in the majority of individuals (85%) language functions are located in the left hemisphere. hemisphere. Karl Wernicke Wernicke’s Area and Wernicke’s Wernicke’s Area Wernicke’s Aphasia associated with lesions to the posterior region of the superior temporal cortex. region Wernicke’s area is responsible for Wernicke’s area language comprehension Wernicke’s aphasics have great difficulty Wernicke’s aphasics understanding speech, even their own understanding their own speech is unintelligible (“word salad”) salad”) Wernicke’s aphasic describing a picture Wernicke’s aphasic showing two boys stealing cookies behind their mothers back: their “Well this is … mother is away here working her work out o’here to get her o’here to better, but when she’s looking, the two boys looking in the other part. One their small tile into her time here. She’s working another time because she’s getting, too …” …” Wernicke’s Area and Wernicke’s Wernicke’s Area Wernicke’s Aphasia Speech is fluent, but unintelligible Poor comprehension Semantic paraphasias (incorrect use of words) Semantic paraphasias Anomia (difficulty naming objects) Impaired repetition of words and sentences and Impaired words. words. Impaired repetition of words and sentences and Impaired words. words. Agraphia (inability to write) usually present Whereas Broca’s aphasics are acutely aware of their problem, acutely of Wernicke’s aphasics often are not. Wernicke’s aphasics They will vehemently deny that vehemently that anything is wrong, and think that everyone else has gone crazy. everyone Great knowledge about the functions of different brain areas has come from studying aphasia… The language areas viewed with FMRI... language Hemi-Neglect • Usually caused by damage to right parietal lobe • Patient “neglects” contralateral hemi-space • May also “neglect” (or deny) contralateral side of the body Some Examples… Line Bisection Task normal patient Patients’ Drawings… Experimenter’s Model Patient’s Reproduction More Patients’ Drawings… A little house-hunting? Are these houses identical? Yes. Are you sure? Yes. So, which would you choose to live in? The bottom one. It seems more cozy… Bisiach & Luzzatti (1978) Patients with visual neglect also show “imagery neglect.” • Milanese neglect patients asked to imagine the view from Piazza del Duomo. • Asked to imagine viewing the Piazza when looking toward the cathedral. • Patients ignored all landmarks to the imagined left side Enough about outright damage… Enough What about “crossWhat wiring”? wiring”? Vilayanur S. Vilayanur S. Ramachandran – Ramachandran University of University California, San Diego. California, Phantom Limb (discussed previously by Dr. Short). by Sensory Representation in the Human Brain Sensory What seems to be happening: What Synaesthesia Synaesthesia – Synaesthesia = a union, or overlap of union, sensory experiences sensory –When When C, an 21 year old undergraduate is shown standard black digits (1, 2, 3, 4) her identification of each digit is accompanied by a photism - a conscious experience of a photism conscious highly specific color. highly 2, 3, 4, 5, A B C D Alphanumeric-Colour Synaesthesia Alphanumeric – “It is difficult to explain . . . I see what you It see. I know the numbers are in black, but as soon as I recognize them I automatically see in my mind a particular colour . . . as soon as I recognize the form colour as of 7 it has to be yellow.” People vary widely in memory skills, but some people are truly extraordinary... These people are sometimes called: Savants Mnemonists (or memorists) Eidetic imagers Photographic memorizers Examples Stratton (1917) studied of a group of Jewish scholars who had allegedly memorized thousands of pages of the Talmud. In his tests, Stratton found 6 men who could... Recite any page he chose. Recite any word in any position of any page! The conductor Toscanini claimed to have perfectly memorized every note for every instrument of over 250 symphonies and 100 operas. Marek tested this claim. T. correctly wrote down instrumental parts of 25 different musical works (which Marek chose). Luria studied a man in Russia (S.) for 30 years. One day, S. showed up at Luria's lab, asking to be tested, worried about losing his mind. S. had an unbelievable ability to memorize, without really trying. For example, he could listen to a series of 75 words, and repeat them in perfect order... ... about 5 years later! S. had an uncontrollable ability to create and remember associations. Luria asked S. to memorize an equation: S. took 7 minutes to make up a “story” Does this seem very memorable? Well, 15 years later, Luria asked S. to recall the equation. No problem. Rajan Mahadevan can examine a 20 x 20 array of digits for 30 seconds & reproduce it perfectly 6 months later. Sounds easy? Here, try for yourself: 5 3 9 4 7 5 3 9 4 7 5 3 9 4 7 5 3 9 4 7 6 4 1 2 7 6 4 1 2 7 6 4 1 2 7 6 4 1 2 7 4 9 8 7 5 4 9 8 7 5 4 9 8 7 5 4 9 8 7 5 3 1 5 4 9 3 1 5 4 9 3 1 5 4 9 3 1 5 4 9 8 5 2 0 2 8 5 2 0 2 8 5 2 0 2 8 5 2 0 2 3 9 0 0 9 3 9 0 0 9 3 9 0 0 9 3 9 0 0 9 0 7 5 2 1 0 7 5 2 1 0 7 5 2 1 0 7 5 2 1 2 3 8 4 3 2 3 8 4 3 2 3 8 4 3 2 3 8 4 3 6 9 4 0 7 6 9 4 0 7 6 9 4 0 7 6 9 4 0 7 0 2 1 1 0 0 2 1 1 0 0 2 1 1 0 0 2 1 1 0 2 4 9 7 2 2 4 9 7 2 2 4 9 7 2 2 4 9 7 2 7 1 2 8 9 7 1 2 8 9 7 1 2 8 9 7 1 2 8 9 7 7 5 3 4 7 7 5 3 4 7 7 5 3 4 7 7 5 3 4 3 8 1 0 6 3 8 1 0 6 3 8 1 0 6 3 8 1 0 6 9 2 6 8 3 9 2 6 8 3 9 2 6 8 3 9 2 6 8 3 1 9 2 4 8 1 9 2 4 8 1 9 2 4 8 1 9 2 4 8 4 6 8 9 7 4 6 8 9 7 4 6 8 9 7 4 6 8 9 7 5 3 1 6 4 5 3 1 6 4 5 3 1 6 4 5 3 1 6 4 2 0 9 2 5 2 0 9 2 5 2 0 9 2 5 2 0 9 2 5 6 5 8 5 2 6 5 8 5 2 6 5 8 5 2 6 5 8 5 2 In 1983, he set a World Record by reciting π to... 31, 811 digits! “Now, at school, I was forced to sit in classes to take notes and exams, to use textbooks that were flat impersonal, deadly. What had been fun, delightful when I did it my own way became an aversion, an ordeal, when I had to do it to order. “ -- Oliver Sacks (Uncle Tungsten: Memories of a chemical boyhood) Suggested readings: Suggested Anything by Oliver Sacks: Sacks: The Man Who Mistook His Wife for a Hat (1985) Wife The Island of the Colorblind (1997) Colorblind Awakenings (1973, rev. ed. 1990) ed. An Anthropologist on Mars (1995) Mars ...
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